1) Field of the Invention
The present invention relates to an image obtaining apparatus which obtains picture images of an object without direct contact therewith. The invention relates particularly to an image obtaining apparatus which has functions of detecting the position (the distance from the image obtaining apparatus), the tilt, and the attitude of the object.
2) Description of the Related Art
There are conventional image obtaining apparatuses which obtain images of an object whose image is to be obtained (hereinafter will be simply called the “object”) without direct contact therewith, while detecting the position, the tilt, or the attitude of the object.
Such an image obtaining apparatus has a distance sensor 100 using the optical triangulation technique as shown in FIG. 13.
In the distance sensor 100 of FIG. 13, a light source 101, which projects laser light, projects a spotlight (laser light) to a measurement object via a lens 102, and an optical position detecting sensor (hereinafter will be simply called the “position sensor”) 103, such as a PSD (Position Sensitive Detector), detects light reflected from the measurement object. In this instance, there is a lens 104 interposed between the position sensor 103 and the measurement object.
In this distance sensor 100, the reflection angle of the reflected light depends on the distances from the distance sensor 100 to the measurement objects A and B. Thus, utilizing the fact that light spot positions A′ and B′ depend on the distances from the distance sensor 100 to the measurement objects A and B, the distances from the distance sensor 100 to the measurement objects A and B are measured based on the light spot positions A′ and B′.
Further, as an apparatus for measuring the distance to the measurement object, the following patent document 1, for example, discloses a distance measuring device 100a as shown in FIG. 14(a) and FIG. 14(b).
The distance measuring device 100a of FIG. 14(a) and FIG. 14(b) includes: a CCD camera 110 with a horizontal angle of view α (see FIG. 14(a)) and a vertical angle of view β (see FIG. 14(b)); a pair of laser light sources 111a and 111a, provided on each side of the CCD camera, having a radiation angle θ for emitting radial right-angle parallel laser light 111 and 111; and an operation unit 112. Here, the CCD camera 110 has a fixed focus lens 110a and a CCD (Charged Coupled Device) 111b, which is an optical/electrical converter.
As shown in FIG. 15(a) and FIG. 15(b), in the distance measuring device 100a, the operation unit 112 calculates e.g., the distance of a measurement object C based on the positions of the bright lines (bright lines due to light projection from laser sources 111a and 111a) 121 and 122 on the measurement object C in a picture image 120 which is obtained by the CCD camera 110 with linear light projected on the measurement object C from the laser light sources 111a and 111a. Here, detection lines 123 through 125 in FIG. 15(b) are for detecting the positions of the bright lines 121 and 122.
The distance sensor 100 of FIG. 13 only has a function of obtaining the distance of the measurement object. Thus, the above-described conventional image obtaining apparatus requires two or more distance sensors 100 to detect the tilt (two-dimensional information) of the object. In addition, the apparatus requires three or more distance sensors 100 to detect the attitude (three-dimensional information) of the object. In such cases, the size of the image obtaining apparatus is increased, and cost is also increased.
In addition, the light sources of such distance sensors 100 are not as reasonable as LED (Light Emitting Diode), and expensive laser light sources are used therein. This also increases the cost of the apparatus. Further, the position sensors 103 is in need of detecting the light spot positions of the reflected light, which also increase the size of the apparatus.
Furthermore, the above-described distance measuring device 100a of FIG. 14(a) and FIG. 14(b) also uses a laser light source as a light source for projecting linear light, so that cost is increased.
Here, if the distance measuring device 100a uses an inexpensive LED as a light source 111a, both ends of the bright lines in the image 120 obtained by the CCD camera 110 become dim, or they are blurred and widened, so that sufficient performance cannot be expected.
Further, in the distance measuring device 100a, each light source 111a projects linear light, having a specific spread (that is, radiation angle θ) in one direction, to the measurement object C, and the lengths of the bright lines 121 and 122 in a screen image 120 obtained by the CCD camera 110 are always the same irrespective of the distance of the measurement object C.
Accordingly, as shown in FIG. 16(a), for example, if the measurement object goes away, the bright lines 121 and 122 lie off the measurement object C, as shown in FIG. 16(b), and as a result, an expected detection becomes unavailable.
(Patent Document 1) Japanese Patent Application Publication No. 2000-230807